1. Field of the Invention
The invention relates to integrated circuits, and, in one embodiment, particularly to analyses of inkjet print head heater chips.
2. Description of the Related Art
Inkjet printing devices such as inkjet printers, all-in-one devices, multifunction devices, and the like, typically uses a print controller or a printer host to control and to communicate with an inkjet print head. A thermal inkjet print head generally has a heater chip. The heater chip typically includes logic circuitry, a plurality of power transistors, and a set of heaters or resistors, among other things. A hardware or software printer driver will selectively address or energize the logic circuitry such that appropriate resistors are heated for printing. In some heater chip designs, the heater chip includes memory used to store information about the print head. Data stored in the memory is used to identify the print head to determine if the print head is a monochrome print head, a color print head or a photograph quality print head. Data stored in the memory is used to keep track of ink usage.
To monitor and to characterize the functionality of the heater chip, a variety of analytical or monitoring methods, and electrical and material analyses are used to analyze the materials layered in the heater chip and the semiconductor devices of the heater chip. For example, an electrical method is performed by electrically measuring structures that help monitor critical process parameters on every wafer. The electrically measured results of die process monitor (“DPM”) structures on the wafer are compared against a predetermined specification. Examples of electrically characterized parameters include sheet resistance, effective line width, and the like. While an electrical method provides a fast indication of process variation and problems, the electrical method does not generally provide a complete characterization. For example, an electrical monitoring method can generally indicate problems, but rarely can determine a root cause of the problem.
On the other hand, material methods are performed using different metrologies in terms of dimension, composition, topology, and the like. For example, material methods such as sectional analysis or cross-section analysis are used to characterize a print head chip. Using sectional analysis, heater chip characteristics such as devices or film features, information on critical dimension, composition profiles, topology as well as material interaction can be collected. Once the information has been collected, other analyses such as process control and failure analysis can use the information to assist in manufacturing processes. For the printhead heater chip, the heater chip analysis becomes even more important since heater chip characteristics such as the film stack thickness needs to be precisely controlled in order to achieve required thermal performance.
Section analysis is performed by grinding and polishing a thin film stack at a location of interest at the heater chip, followed by optical and e-beam inspection. Section analysis is usually very tedious and time consuming. For example, many sectional cuts are necessary to complete a thorough analysis and inspection.